DJ fuel consumption and ignition timing.

[PetenAli]

Just got back from Dartmoor and worked out the fuel consumption - we got 24.508474mpg! Worked this out using sat nav to calculate exact miles and brimmed the tank at start and finish. This was in a Westy pop top with two up, all our gear and two bikes on the back. On the return journey we also had a strong side wind most of the way. Timing was set as above i.e. 10 degrees btdc and using 98 ron (Shell V Power on this occasion although Sainsbury's is cheaper). Idle set to 800rpm.

Last time I seriously measured fuel consumption was a trip to Snowdonia with 4 up and climbing gear etc but no bikes. It was timed at 5 degrees btdc and using 95 ron. It made just over 20mpg then so I'm quite pleased with this improvement.

Had some thoughts as follows:

I needed to use sat nav to calculate the distance as my 15" BFGs make the odometer under read by about 7% (and, thinking about it, that totally throws my calculation on the Snowdon trip mentioned above).

Following on from that - I wonder how much difference large 15" tyres make to fuel consumption? I have a set of 6 x 14" original Syncro steel rims but will have to save up for some tyres before I can try them out.

Brimming the tank is very important. It took me a long time to get it right to the top and I added about 5 litres over and above what I would normally call a full tank. I kept stopping to check that I wasn't losing fuel as it seemed to take ages before I could see fuel at the top of the pipe.

[syncropaddy]

Had some thoughts as follows:

I wonder how much difference large 15" tyres make to fuel consumption? I have a set of 6 x 14" original Syncro steel rims but will have to save up for some tyres before I can try them out.

You can win or loose with a wheel upgrade. 14" Syncros came with either 185 R 14 or 205 R14 tyres with final drive ratios to match. By fitting, say, 215/75/15 BFG A/Ts on Mefro wheels your cruising speed consumption should improve but you will loose some flexibility getting there so around town you may increase consumption. Long motorway hills and head winds are consumption killer along with weight, driving style and conditions.

[mm289]

Just on the STP theme, there are a lot of injection/fuel/combustion improvers & cleaners around - won't enter the fray on that one as it tends to get quite passionate!

An alternative (long term, gauranteed) fix I would recommed is to get the injectors cleaned. There are a couple of threads around on here/BW about it, but my local shop charges £10+VAT per injector to test/clean/fit new o-rings.

This gives a real improvement in flow and spread whereas the additives are a lot harder to prove - worth having a think about

Look at this site for local guys to you http://www.asnu.com/centres.htm

MM

[syncrosimon]

Equally running mainly on Shell V-Power has the same effect. Tis expensive though.

[PetenAli]

Look at this site for local guys to you http://www.asnu.com/centres.htm" onclick="window.open(this.href);return false;

Two are within 5 minutes drive - thanks very much!

Pete

[syncrosimon]

Equally running mainly on Shell V-Power has the same effect. Tis expensive though.

It is the most advanced fuel with conditioners that keep things clean.

[PetenAli]

It is the most advanced fuel with conditioners that keep things clean.

So there is a qualitative difference between V Power and, for example, Sainsbury's 98ron? This is all fascinating to someone who is just not an engineer!

[mm289]

Equally running mainly on Shell V-Power has the same effect. Tis expensive though.

Definately makes a difference running with stuff like V-power, from what i have read they put additional cleaning additives in that the cheaper brands don't.

The injector cleaning will clean out any muck in one hit though - not sure how much or how long you would have to run with V-power to achieve the same effect. If you ask for a pre/post flow report you will be surprised how gummed up injectors that have had over 100k miles on them can be!

MM

[syncropaddy]

It is the most advanced fuel with conditioners that keep things clean.

So there is a qualitative difference between V Power and, for example, Sainsbury's 98ron? This is all fascinating to someone who is just not an engineer!

AFAIK V Power is rated at 99 RON. We dont get V Power or Total Excellium over here but I use it every time I'm in the UK or on the Continent. I did a consumption test on a Passat 170 a few years ago and the 'premium' fuels are definitely better than the standard stuff.

[syncrosimon]

I think that the DJ's high compression ration makes better use of V-power type fuels when tuned up right.

http://www.youtube.com/watch?v=gQghB4as ... re=related" onclick="window.open(this.href);return false;

[KINGPRAWN]

I think that the DJ's high compression ration makes better use of V-power type fuels when tuned up right.

http://www.youtube.com/watch?v=gQghB4as ... re=related" onclick="window.open(this.href);return false;

so... can the dj reset its ecu to the relative fuel or is it just getting what it needs when you go 98ron??

[syncropaddy]

I think that the DJ's high compression ration makes better use of V-power type fuels when tuned up right.

http://www.youtube.com/watch?v=gQghB4as ... re=related" onclick="window.open(this.href);return false;

so... can the dj reset its ecu to the relative fuel or is it just getting what it needs when you go 98ron??

At standard settings, its getting what it needs. I dont think ECUs are that clever ..... certainly not then anyway!!

[PetenAli]

http://www.youtube.com/watch?v=gQghB4as" onclick="window.open(this.href);return false; ... re=related

Info regarding torque on this clip is interesting to a heavy Syncro owner. It makes my subjective non engineer comments much earlier in this thread seem as if they might have some validity after all.

Pete

[syncropaddy]

http://www.youtube.com/watch?v=gQghB4as" onclick="window.open(this.href);return false; ... re=related

Info regarding torque on this clip is interesting to a heavy Syncro owner. It makes my subjective non engineer comments much earlier in this thread seem as if they might have some validity after all.

Pete

Premium fuels have other benefits as well, lower emissions and engine cleaning properties are just some. I wish we had it over here.

[toomanytoys]

I think that the DJ's high compression ration makes better use of V-power type fuels when tuned up right.

http://www.youtube.com/watch?v=gQghB4as ... re=related" onclick="window.open(this.href);return false;

so... can the dj reset its ecu to the relative fuel or is it just getting what it needs when you go 98ron??

At standard settings, its getting what it needs. I dont think ECUs are that clever ..... certainly not then anyway!!

Its basically a look up table.. very simple design..
It looks for signals.. basically
either idle/no idle/full throttle
Engine rpm
airflow
and engine temperature

Then for a given set of numbers and combinations it delivers "X" amount of fuel...
If any thing is worn or mal adjusted, air leaks etc etc.. then it puts it all into a cocked hat and delivers less performance and less mpg..

Syncrosimon is getting very good mpg.. and some very valid reasons why.. its a nice fresh vw engine, its had the injection system fully maintained and prob a good nee parts in it (correct me if I am wrong Si) and its been set up very well...
the drivers right foot and style can make a big difference also..

I used to see 24mpg out of my 1.9DG doka on a run,.. but with a tired engine now and prob driving it harder, I am lucky to see 21....